Homeowners are responsible for testing water in their wells for bacteria, nitrates, pH and total dissolved solids.  Bacteria and nitrates are of specific concern because of potential health-related problems that could be encountered. 

Contact your local health department to see if free testing is available or for any guidelines that should be followed.   

Also contact the local county extension agent and ask for "Home-A-Syst" information on wells used for drinking water.  The Cooperative Extension Service's Home-A-Syst program helps homeowners evaluate ground and surface water quality on their property.

The EPA and the Kentucky Division of Water do not regulate contaminants in private wells.

Bacteria in Private Drinking Water Wells
Just because water is clear and smells OK does not mean the water is free from bacteria.  You cannot directly smell unsafe levels of bacteria.

Coliform bacteria are microorganisms found in the intestines of warm-blooded animals (fecal coli).  These bacteria are also found in soil, on vegetation and in surface water runoff.  Finding coliform bacteria is an indicator of water contamination.  There is a potential for other disease-producing organisms such as intestinal parasites and viruses to be present if coliform bacteria is found.

Coliform bacteria are usually filtered out as water passes through the soil to the groundwater table.  However, poorly-constructed or unsealed wells, cracked cisterns, fractured rock outcroppings, sinkholes and quarries may provide a path for coliform bacteria to enter groundwater.  If bacteria enter the well, they can rapidly multiply.  Once in the groundwater, bacteria can easily pollute drinking water.

Drinking water drawn from private wells or cisterns should be tested for the presence of bacteria at least once a year.

Testing for bacteria will generally cost the homeowner $10 to $25 per sample.  The homeowner should contact the local health department to see if it offers "once-a-year" water testing for a private drinking water well. 

If the laboratory tests confirm the presence of coliform bacteria at unsafe levels in your water supply, contact the local health department for recommendations.  The source of contamination will have to be determined, and the entire water system will have to be disinfected.  Disinfection usually involves shock chlorination process.

For short-term disinfection of small amounts of water, boiling the water is recommended.  Water can be boiled at a rolling boil for at least three minutes to kill disease-causing bacteria. 

Nitrate in Private Drinking Water Wells
Nitrate is a compound formed when nitrogen combines with oxygen.  Nitrogen occurs naturally in the soil in organic forms.  Organic nitrogen results from decaying plant and animal matter.  Nitrogen is also a commercial nutrient applied to lawns, gardens and fields for crop production.  Since nitrates are very soluble and do not bind to soil particles, nitrates have a high potential to migrate to groundwater.  Because nitrates do not evaporate, nitrates and nitrites are likely to remain in water until consumed by plants or other organisms.

Sources of nitrate include fertilizers, septic systems, animal feedlots, straight-pipe sewage, municipal and industrial wastewater, and urban drainage.  Underground soil and bedrock structure and the direction of groundwater flow influence when and where nitrate is found.  In some areas, nitrate contamination may be associated with other groundwater contaminants.  Elevated levels of nitrate in well water are often used as an indicator of improper well construction or location, overuse of chemical fertilizers, or improper disposal of human or animal waste.

Although nitrate is found naturally, high levels in drinking water pose a serious acute health threat for infants less than six months of age.  In 1962, the U.S. Public Health Service adopted drinking water standards and set the recommended limit for nitrate-nitrogen at 10 mg/L (expressed as milligrams per liter).

Nitrate is changed to nitrite in the stomachs of small infants because their digestive system is still developing. The nitrite interferes with the blood's ability to carry oxygen, and symptoms of suffocation or blue baby syndrome (also called methemoglobinemia) can occur.  The nitrite oxidizes iron in the hemoglobin of red blood cells to form methemoglobin, which lacks the oxygen-carrying ability of hemoglobin.  Water with less than 10 mg/L nitrate as Nitrogen (NO3-N) is generally safe for consumption.  Nitrate levels greater than 10 mg/L should not be fed to infants, and an alternative water source should be found. 

Pregnant women may be less able to tolerate nitrate, and nitrate in the milk of nursing mothers may affect infants directly.  Pregnant or nursing women should not consume water containing more than 10 mg/L nitrate directly, added to food products or beverages (especially in baby formula).  Other domestic use of this water supply is acceptable, including washing and bathing.

Available health information suggests that healthy adults and children older than one year of age are not affected by high  nitrate levels.  Because adults and children consume solid food, nitrate generally does not cause a problem.  Research is underway to ascertain if nitrate causes chronic illness.

A nitrate test is recommended for all wells, especially for wells serving infants under six months of age and pregnant or nursing mothers.  If the nitrate levels are over 10 mg/L, the water should not be fed to infants under six months of age or used to prepare formula.

If nitrate levels remain less than 5 mg/L, then testing the well water once every two or three years should be adequate. If the results are between 5 and 10 mg/L, more frequent, perhaps annual, testing can be considered to monitor fluctuations in nitrate concentration.

The homeowner should anticipate nitrate testing to cost about $10 to $25 per sample.  Homeowners should check with their local health department to see if "once-a-year" private well testing is available.  The Kentucky Cooperative Extension Service is also a useful source of information on nitrates.

Do not heat or boil water for consumption containing nitrate!  Heating or boiling water containing nitrate will not remove the nitrate and may actually concentrate the levels.  Options to consider in removing nitrate include using bottled water for drinking and for food and beverage preparation or installing a home water treatment unit.  Follow the instructions precisely on home water treatment units, including replacement of the filter routinely, to avoid potential problems of water contamination.  Contact your local health department on techniques to remove high levels of nitrate.

Other Resources on Bacteria and Nitrates in Wells:
Contact the National Ground Water Association (NGWA) at http://www.ngwa.org/ for comprehensive information on bacteria in private wells from their Web page at http://www.ngwa.net/public/bac_faq.html.  They also have information available on nitrate.  Search the NGWA Web site for available information on nitrate.

US EPA provides fact sheets on nitrates and bacteria.  For nitrates, see http://www.epa.gov/safewater/dwh/c-ioc/nitrates.html.  For bacteria (E. coli) see http://www.epa.gov/safewater/ecoli.html.